From ee52d818dc8711c39bbc49fb56f729ef497e7013 Mon Sep 17 00:00:00 2001
From: 13659257719 <819781841@qq.com>
Date: Tue, 7 Nov 2023 10:56:44 +0800
Subject: [PATCH] =?UTF-8?q?[inula-dev-tools]<feat>=20=E6=98=BE=E7=A4=BA?=
 =?UTF-8?q?=E5=88=97=E8=A1=A8=E7=BB=84=E4=BB=B6=E5=90=88=E5=85=A5?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../src/components/VList/ItemMap.ts           |  80 +++++++++++
 .../src/components/VList/VList.less           |  26 ++++
 .../src/components/VList/VList.tsx            | 135 ++++++++++++++++++
 3 files changed, 241 insertions(+)
 create mode 100644 packages/inula-dev-tools/src/components/VList/ItemMap.ts
 create mode 100644 packages/inula-dev-tools/src/components/VList/VList.less
 create mode 100644 packages/inula-dev-tools/src/components/VList/VList.tsx

diff --git a/packages/inula-dev-tools/src/components/VList/ItemMap.ts b/packages/inula-dev-tools/src/components/VList/ItemMap.ts
new file mode 100644
index 00000000..81109df4
--- /dev/null
+++ b/packages/inula-dev-tools/src/components/VList/ItemMap.ts
@@ -0,0 +1,80 @@
+/*
+ * Copyright (c) 2023 Huawei Technologies Co.,Ltd.
+ *
+ * openInula is licensed under Mulan PSL v2.
+ * You can use this software according to the terms and conditions of the Mulan PSL v2.
+ * You may obtain a copy of Mulan PSL v2 at:
+ *
+ *          http://license.coscl.org.cn/MulanPSL2
+ *
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PSL v2 for more details.
+ */
+
+/**
+ * 用于在滚动的过程中，对比上一次渲染的结果和本次需要渲染项
+ * 确保继续渲染项在新渲染数组中的位置和旧渲染数组中的位置不发生改变
+ */
+export default class ItemMap<T> {
+
+  // 不要用 indexOf 进行位置计算，它会遍历数组
+  private lastRenderItemToIndexMap: Map<T, number>;
+
+  constructor() {
+    this.lastRenderItemToIndexMap = new Map();
+  }
+
+  public calculateReSortedItems(nextItems: T[]): (T|undefined)[] {
+    if (this.lastRenderItemToIndexMap.size === 0) {
+      nextItems.forEach((item, index) => {
+        this.lastRenderItemToIndexMap.set(item, index);
+      });
+      return nextItems;
+    }
+
+    const nextRenderItems: T[] = [];
+    const length = nextItems.length;
+    const nextRenderItemToIndexMap = new Map<T, number>();
+    const addItems = [];
+
+    // 遍历 nextItems 找到复用 item 和新增 item
+    nextItems.forEach(item => {
+      const lastIndex = this.lastRenderItemToIndexMap.get(item);
+      // 处理旧 item
+      if (lastIndex !== undefined) {
+        // 使用上一次的位置
+        nextRenderItems[lastIndex] = item;
+        // 记录位置
+        nextRenderItemToIndexMap.set(item, lastIndex);
+      } else {
+        // 记录新的 item
+        addItems.push(item);
+      }
+    });
+
+    // 处理新增 item，翻转数组，后面在调用 pop 时拿到的时最后一个，以确保顺序
+    addItems.reverse();
+    for (let i = 0; i < length; i++) {
+      // 优先将新增 item 放置在空位置上
+      if (!nextRenderItems[i]) {
+        const item = addItems.pop();
+        nextRenderItems[i] = item;
+        nextRenderItemToIndexMap.set(item, i);
+      }
+    }
+
+    // 剩余新 item 补在数组后面
+    for (let i = addItems.length - 1; i >= 0; i--) {
+      const item = addItems[i];
+      nextRenderItemToIndexMap.set(item, nextRenderItems.length);
+      nextRenderItems.push(item);
+    }
+
+    // 如果 nextRenderItems 中存在空 index，nextItems 已经耗尽，不用处理
+    // 确保新旧数组中 item 的 index 值不会发生变化
+    this.lastRenderItemToIndexMap = nextRenderItemToIndexMap;
+    return nextRenderItems;
+  }
+}
diff --git a/packages/inula-dev-tools/src/components/VList/VList.less b/packages/inula-dev-tools/src/components/VList/VList.less
new file mode 100644
index 00000000..27d47999
--- /dev/null
+++ b/packages/inula-dev-tools/src/components/VList/VList.less
@@ -0,0 +1,26 @@
+/*
+ * Copyright (c) 2023 Huawei Technologies Co.,Ltd.
+ *
+ * openInula is licensed under Mulan PSL v2.
+ * You can use this software according to the terms and conditions of the Mulan PSL v2.
+ * You may obtain a copy of Mulan PSL v2 at:
+ *
+ *          http://license.coscl.org.cn/MulanPSL2
+ *
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PSL v2 for more details.
+ */
+
+.container {
+  position: relative;
+  overflow-y: auto;
+  height: 100%;
+  width: 100%;
+}
+
+.item {
+  position: absolute;
+  width: 100%;
+}
diff --git a/packages/inula-dev-tools/src/components/VList/VList.tsx b/packages/inula-dev-tools/src/components/VList/VList.tsx
new file mode 100644
index 00000000..86c148c3
--- /dev/null
+++ b/packages/inula-dev-tools/src/components/VList/VList.tsx
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2023 Huawei Technologies Co.,Ltd.
+ *
+ * openInula is licensed under Mulan PSL v2.
+ * You can use this software according to the terms and conditions of the Mulan PSL v2.
+ * You may obtain a copy of Mulan PSL v2 at:
+ *
+ *          http://license.coscl.org.cn/MulanPSL2
+ *
+ * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
+ * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
+ * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
+ * See the Mulan PSL v2 for more details.
+ */
+
+/**
+ * 内部只记录滚动位置状态值
+ * data 数组更新后不修改滚动位置，只有修改 scrollToItem 才会修改滚动位置
+ */
+import { useState, useRef, useEffect, useMemo } from 'openinula';
+import styles from './VList.less';
+import ItemMap from './ItemMap';
+import { debounceFunc } from '../../utils/publicUtil';
+
+interface IProps<T extends { id: number | string }> {
+  data: T[];
+  maxDeep: number;
+  width: number; // 暂时未用到，当需要支持横向滚动时使用
+  height: number; // VList 的高度
+  children?: any; // inula 组件
+  itemHeight: number;
+  scrollToItem?: T; // 滚动到指定项位置，如果该项在可见区域内，不滚动，如果补在，则滚动到中间位置
+  onRendered: (renderInfo: RenderInfoType<T>) => void;
+  filter?: (data: T) => boolean; // false 表示该行不显示
+}
+
+export type RenderInfoType<T> = {
+  visibleItems: T[];
+}
+
+function parseTranslate<T>(data: T[], itemHeight: number) {
+  const map = new Map<T, number>();
+  data.forEach((item, index) => {
+    map.set(item, index * itemHeight);
+  })
+  return map;
+}
+
+export function VList<T extends { id: number | string }>(props: IProps<T>) {
+  const { data, maxDeep, height, width, children, itemHeight, scrollToItem, onRendered } = props;
+  const [scrollTop, setScrollTop] = useState(Math.max(data.indexOf(scrollToItem), 0) * itemHeight);
+  const renderInfoRef: { current: RenderInfoType<T> } = useRef({
+    visibleItems: [],
+  });
+  const [indentationLength, setIndentationLength] = useState(0);
+
+  // 每个 item 的 translateY 值固定不变
+  const itemToTranslateYMap = useMemo(() => parseTranslate(data, itemHeight), [data]);
+  const itemIndexMap = useMemo(() => new ItemMap<T>(), []);
+  const containerRef = useRef<HTMLDivElement>();
+
+  useEffect(() => {
+    onRendered(renderInfoRef.current);
+  });
+
+  useEffect(() => {
+    debounceFunc(() => setIndentationLength(Math.min(12, Math.round(width / (2 * maxDeep)))));
+  }, [width]);
+
+  useEffect(() => {
+    if (scrollToItem) {
+      const renderInfo = renderInfoRef.current;
+      // 在显示区域，不滚动
+      if (!renderInfo.visibleItems.includes(scrollToItem)) {
+        const index = data.indexOf(scrollToItem);
+        // 显示在页面中间
+        const top = Math.max(index * itemHeight - height / 2, 0);
+        containerRef.current.scrollTo({ top: top });
+      }
+    }
+  }, [scrollToItem]);
+
+  // 滚动事件会频繁触发，通过框架提供的代理会有大量计算寻找 dom 元素，直接绑定到原生事件上减少计算量
+  useEffect(() => {
+    const handleScroll = event => {
+      const scrollTop = event.target.scrollTop;
+      setScrollTop(scrollTop);
+    };
+    const container = containerRef.current;
+    container.addEventListener('scroll', handleScroll);
+    return () => {
+      container.removeEventListener('scroll', handleScroll);
+    };
+  }, []);
+
+  const totalHeight = itemHeight * data.length;
+  const maxIndex = data.length; // slice 截取渲染 item 数组时最大位置不能超过自然长度
+  // 第一个可见 item index
+  const firstInViewItemIndex = Math.floor(scrollTop / itemHeight);
+  // 可见区域前最多冗余 4 个 item
+  const startRenderIndex = Math.max(firstInViewItemIndex - 4, 0); // index 不能小于 0
+  // 最多可见数量
+  const maxInViewCount = Math.floor(height / itemHeight);
+  // 最后可见 item index
+  const lastInViewIndex = Math.min(firstInViewItemIndex + maxInViewCount, maxIndex);
+  // 记录可见 items
+  renderInfoRef.current.visibleItems = data.slice(firstInViewItemIndex, lastInViewIndex);
+  // 可见区域后冗余 4 个 item
+  const lastRenderIndex = Math.min(lastInViewIndex + 4, maxIndex);
+  // 需要渲染的 item
+  const renderItems = data.slice(startRenderIndex, lastRenderIndex);
+  // 给 items 重新排序，确保未移出渲染数组的 item 在新的渲染数组中位置不变，这样在 diff 算法比较后，这部分的 dom 不会发生更新
+  const nextRenderList = itemIndexMap.calculateReSortedItems(renderItems);
+  const list = nextRenderList.map((item, index) => {
+    if (!item) {
+      return null;
+    }
+    return (
+      <div
+        key={String(i)} // 固定 key 值，这样就只会更新 translateY 的值
+        className={styles.item}
+        style={{ transform: `translateY(${itemToTranslateYMap.get(item)}px)` }}
+      >
+        {children(item,indentationLength)}
+      </div>
+    );
+  });
+
+  return (
+    <div ref={containerRef} className={styles.container}>
+      {list}
+      <div style={{ marginTop: totalHeight }}></div>
+    </div>
+  );
+}